NCERT Solutions for Class 4th Maths Chapter 1 Drawing 2D shapes, marking right angles and naming angles — Let Us Try
Book page 23 Updated on2026-09-19
Q1.
Draw a 2D shape that has less than 5 angles. Draw a 2D shape with more than 5 angles.
One of the two dot grids given in the book.
Answer
Remember: a shape has as many angles as it has sides.
Less than 5 angles — so 3 or 4 sides
a triangle — 3 sides, 3 angles;
a square or a rectangle — 4 sides, 4 angles.
More than 5 angles — so 6 sides or more
a hexagon — 6 sides, 6 angles;
an octagon — 8 sides, 8 angles.
How to draw them on the dot grid
For the triangle, join any 3 dots that are not in one straight line.
For the hexagon, go round a middle dot and join 6 dots one after another, coming
back to where you started.
Sample answer: On the left grid I drew a rectangle (4 angles).
On the right grid I drew a hexagon (6 angles).
Why it happens: Every time a side ends, the shape has to turn a
corner. So counting sides is the same as counting angles.
Q2.
Mark the right angles and write the number of right angles in each figure.
The six figures printed in the book.
Answer
Test every corner with the corner of your folded paper.
Figure
What it is
Number of right angles
1
rectangle
4
2
parallelogram
0
3
triangle
1
4
trapezium
0
5
slanting four-sided shape
0
6
rectangle, drawn tilted
4
The same figures with the number of right angles written under each one.
Tip: Figure 6 is tilted on the page, but tilting does not
change an angle. Turn your paper checker along with the shape and it still fits.
Why it happens: A right angle is the corner of a square. In the
rectangle and the tilted rectangle every side stands square to the next, so all 4 corners
fit the checker. In the leaning shapes the corners have opened out or closed up, so none
fits.
Q3.
Which of the above shapes have only right angles?
The six figures printed in the book.
Answer
Only figures 1 and 6.
Figure 1 is a rectangle — all 4 of its angles are right angles.
Figure 6 is a rectangle drawn tilted — all 4 of its angles are right angles
too.
Figure 3 has one right angle, but its other two angles are acute, so it does not have
only right angles. Figures 2, 4 and 5 have none at all.
Why it happens: A four-sided shape can have all its angles equal
to a right angle — that shape is a rectangle (and a square is a rectangle too). A
triangle never can: if two of its angles were right angles, its other two sides would
never meet.
Q4.
Observe the following shapes. Identify the shape that has: 2 right angles, 1 acute, and 1 obtuse angle .
The fourteen shapes printed in the book.
Answer
Shape 2 (and shape 7 as well).
How to look: put your paper checker on each of the four corners in turn.
In shape 2 the checker fits exactly at two
corners, one corner is narrower than the checker (acute) and one
is wider (obtuse).
Shape 7 is the same kind of shape, so it also has 2 right, 1 acute and 1
obtuse angle.
Shapes 2 and 7 are ringed.
Why it happens: These are four-sided shapes with one pair
of parallel sides and one side standing square to them. That square side makes two right
angles, and the slanting side makes one narrow and one wide angle.
Q5.
Observe the following shapes. Identify the shape that has: 1 right, 2 obtuse, and 1 acute angle .
The fourteen shapes printed in the book.
Answer
Shape 10.
One corner fits the paper checker exactly — that is the
right angle.
Two corners are wider than the checker — those are the
obtuse angles.
One corner is much narrower than the checker — that is the
acute angle.
1 right + 2 obtuse + 1 acute = 4 angles, so it is a four-sided
shape.
Shape 10 is ringed.
Why it happens: A four-sided shape has 4 angles altogether.
Here one corner has stayed square while the shape has been stretched, so one angle is
squeezed narrow and the other two are pushed wide.
Q6.
Observe the following shapes. Identify the shape that has: 2 obtuse, and 2 acute angles .
The fourteen shapes printed in the book.
Answer
Shapes 3, 5, 8, 9, 11 and 13.
Each of these is a leaning four-sided shape — a parallelogram or a
rhombus.
Two opposite corners are narrower than the paper checker
(acute), and the other two are wider (obtuse).
There is no right angle in any of them.
Shapes 3, 5, 8, 9, 11 and 13 are ringed.
Why it happens: These shapes are rectangles that have been
pushed over. Whatever one corner loses, the corner next to it gains, so the narrow and
the wide angles always come in pairs.
Q7.
Observe the following shapes. Identify the shape that has: 4 right angles .
The fourteen shapes printed in the book.
Answer
Shapes 4, 6, 12 and 14.
Shape 6 is a rectangle standing upright.
Shapes 12 and 14 are squares.
Shape 4 is a square drawn tilted, standing on one corner — but its angles
are still right angles.
Put your paper checker on all four corners of each of these. It fits every time.
Shapes 4, 6, 12 and 14 are ringed.
Why it happens: A shape with 4 right angles is a rectangle,
and a square is a rectangle with all four sides equal. Turning it on the page does not
change its angles, so a tilted square still has 4 right angles.